The measurement of electrophysiological signals from a human or animal body generally requires electrodes to be maintained substantially in contact with the subject body. As such signals are generally of small magnitude (e.g., micro volts or less), the electrodes are typically made from, or coated with, gold or another highly conductive material. Conventional electrodes are generally electrically coupled to an amplifier or other signal processing apparatus by means of high conductivity wires that are required to be electrically connected to the actual electrodes. However, the presence of wires connected directly to electrodes in an electrode assembly is inconvenient, particularly, for example, when the electrode assembly is to be applied to a human head. Furthermore, some means of strain relief is necessary to prevent the wires becoming detached from the electrodes as the electrode assembly is moved or manipulated.
A disadvantage associated with soldering the wires to the electrodes is that potentials are generated when the wires and electrodes are of dissimilar conductive metals (due to the galvanic effect). As the electrophysiological signals themselves are of small magnitude, such parasitic potentials constitute substantial unwanted interference. Crimping of the wires to the electrodes is thus advantageous compared to soldering, but disadvantageously requires the electrodes to incorporate a crimping portion. This translates into specialized electrodes of relatively higher cost, which consequently may not be disposable.
A need exists for improved apparatuses for measuring electrophysiological signals from human or animal bodies.